/*
 * Copyright 2002-2015 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.bangcommunity.bbframe.common.utils.lang;

import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Properties;

/**
 * Miscellaneous collection utility methods. Mainly for internal use within the framework.
 *
 * @author Juergen Hoeller
 * @author Rob Harrop
 * @author Arjen Poutsma
 * @since 1.1.3
 */
public abstract class CollectionUtils {

    /**
     * Return {@code true} if the supplied Collection is {@code null} or empty. Otherwise, return
     * {@code false}.
     * 
     * @param collection
     *            the Collection to check
     * @return whether the given Collection is empty
     */
    public static boolean isEmpty(Collection<?> collection) {
        return (collection == null || collection.isEmpty());
    }

    public static boolean isNotEmpty(Collection c) {
        return !isEmpty(c);
    }

    /**
     * Return {@code true} if the supplied Map is {@code null} or empty. Otherwise, return
     * {@code false}.
     * 
     * @param map
     *            the Map to check
     * @return whether the given Map is empty
     */
    public static boolean isEmpty(Map<?, ?> map) {
        return (map == null || map.isEmpty());
    }

    /**
     * Convert the supplied array into a List. A primitive array gets converted into a List of the
     * appropriate wrapper type.
     * <p>
     * <b>NOTE:</b> Generally prefer the standard {@link Arrays#asList} method. This
     * {@code arrayToList} method is just meant to deal with an incoming Object value that might be
     * an {@code Object[]} or a primitive array at runtime.
     * <p>
     * A {@code null} source value will be converted to an empty List.
     * 
     * @param source
     *            the (potentially primitive) array
     * @return the converted List result
     * @see ObjectUtils#toObjectArray(Object)
     * @see Arrays#asList(Object[])
     */
    @SuppressWarnings("rawtypes")
    public static List arrayToList(Object source) {
        return Arrays.asList(ObjectUtils.toObjectArray(source));
    }

    /**
     * Merge the given array into the given Collection.
     * 
     * @param array
     *            the array to merge (may be {@code null})
     * @param collection
     *            the target Collection to merge the array into
     */
    @SuppressWarnings("unchecked")
    public static <E> void mergeArrayIntoCollection(Object array, Collection<E> collection) {
        if (collection == null) {
            throw new IllegalArgumentException("Collection must not be null");
        }
        Object[] arr = ObjectUtils.toObjectArray(array);
        for (Object elem : arr) {
            collection.add((E) elem);
        }
    }

    /**
     * Merge the given Properties instance into the given Map, copying all properties (key-value
     * pairs) over.
     * <p>
     * Uses {@code Properties.propertyNames()} to even catch default properties linked into the
     * original Properties instance.
     * 
     * @param props
     *            the Properties instance to merge (may be {@code null})
     * @param map
     *            the target Map to merge the properties into
     */
    @SuppressWarnings("unchecked")
    public static <K, V> void mergePropertiesIntoMap(Properties props, Map<K, V> map) {
        if (map == null) {
            throw new IllegalArgumentException("Map must not be null");
        }
        if (props != null) {
            for (Enumeration<?> en = props.propertyNames(); en.hasMoreElements();) {
                String key = (String) en.nextElement();
                Object value = props.getProperty(key);
                if (value == null) {
                    // Potentially a non-String value...
                    value = props.get(key);
                }
                map.put((K) key, (V) value);
            }
        }
    }

    /**
     * Check whether the given Iterator contains the given element.
     * 
     * @param iterator
     *            the Iterator to check
     * @param element
     *            the element to look for
     * @return {@code true} if found, {@code false} else
     */
    public static boolean contains(Iterator<?> iterator, Object element) {
        if (iterator != null) {
            while (iterator.hasNext()) {
                Object candidate = iterator.next();
                if (ObjectUtils.nullSafeEquals(candidate, element)) {
                    return true;
                }
            }
        }
        return false;
    }

    /**
     * Check whether the given Enumeration contains the given element.
     * 
     * @param enumeration
     *            the Enumeration to check
     * @param element
     *            the element to look for
     * @return {@code true} if found, {@code false} else
     */
    public static boolean contains(Enumeration<?> enumeration, Object element) {
        if (enumeration != null) {
            while (enumeration.hasMoreElements()) {
                Object candidate = enumeration.nextElement();
                if (ObjectUtils.nullSafeEquals(candidate, element)) {
                    return true;
                }
            }
        }
        return false;
    }

    /**
     * Check whether the given Collection contains the given element instance.
     * <p>
     * Enforces the given instance to be present, rather than returning {@code true} for an equal
     * element as well.
     * 
     * @param collection
     *            the Collection to check
     * @param element
     *            the element to look for
     * @return {@code true} if found, {@code false} else
     */
    public static boolean containsInstance(Collection<?> collection, Object element) {
        if (collection != null) {
            for (Object candidate : collection) {
                if (candidate == element) {
                    return true;
                }
            }
        }
        return false;
    }

    /**
     * Return {@code true} if any element in '{@code candidates}' is contained in '{@code source}';
     * otherwise returns {@code false}.
     * 
     * @param source
     *            the source Collection
     * @param candidates
     *            the candidates to search for
     * @return whether any of the candidates has been found
     */
    public static boolean containsAny(Collection<?> source, Collection<?> candidates) {
        if (isEmpty(source) || isEmpty(candidates)) {
            return false;
        }
        for (Object candidate : candidates) {
            if (source.contains(candidate)) {
                return true;
            }
        }
        return false;
    }

    /**
     * Return the first element in '{@code candidates}' that is contained in '{@code source}'. If no
     * element in '{@code candidates}' is present in '{@code source}' returns {@code null}.
     * Iteration order is {@link Collection} implementation specific.
     * 
     * @param source
     *            the source Collection
     * @param candidates
     *            the candidates to search for
     * @return the first present object, or {@code null} if not found
     */
    @SuppressWarnings("unchecked")
    public static <E> E findFirstMatch(Collection<?> source, Collection<E> candidates) {
        if (isEmpty(source) || isEmpty(candidates)) {
            return null;
        }
        for (Object candidate : candidates) {
            if (source.contains(candidate)) {
                return (E) candidate;
            }
        }
        return null;
    }

    /**
     * Find a single value of the given type in the given Collection.
     * 
     * @param collection
     *            the Collection to search
     * @param type
     *            the type to look for
     * @return a value of the given type found if there is a clear match, or {@code null} if none or
     *         more than one such value found
     */
    @SuppressWarnings("unchecked")
    public static <T> T findValueOfType(Collection<?> collection, Class<T> type) {
        if (isEmpty(collection)) {
            return null;
        }
        T value = null;
        for (Object element : collection) {
            if (type == null || type.isInstance(element)) {
                if (value != null) {
                    // More than one value found... no clear single value.
                    return null;
                }
                value = (T) element;
            }
        }
        return value;
    }

    /**
     * Find a single value of one of the given types in the given Collection: searching the
     * Collection for a value of the first type, then searching for a value of the second type, etc.
     * 
     * @param collection
     *            the collection to search
     * @param types
     *            the types to look for, in prioritized order
     * @return a value of one of the given types found if there is a clear match, or {@code null} if
     *         none or more than one such value found
     */
    public static Object findValueOfType(Collection<?> collection, Class<?>[] types) {
        if (isEmpty(collection) || ObjectUtils.isEmpty(types)) {
            return null;
        }
        for (Class<?> type : types) {
            Object value = findValueOfType(collection, type);
            if (value != null) {
                return value;
            }
        }
        return null;
    }

    /**
     * Determine whether the given Collection only contains a single unique object.
     * 
     * @param collection
     *            the Collection to check
     * @return {@code true} if the collection contains a single reference or multiple references to
     *         the same instance, {@code false} else
     */
    public static boolean hasUniqueObject(Collection<?> collection) {
        if (isEmpty(collection)) {
            return false;
        }
        boolean hasCandidate = false;
        Object candidate = null;
        for (Object elem : collection) {
            if (!hasCandidate) {
                hasCandidate = true;
                candidate = elem;
            } else if (candidate != elem) {
                return false;
            }
        }
        return true;
    }

    /**
     * Find the common element type of the given Collection, if any.
     * 
     * @param collection
     *            the Collection to check
     * @return the common element type, or {@code null} if no clear common type has been found (or
     *         the collection was empty)
     */
    public static Class<?> findCommonElementType(Collection<?> collection) {
        if (isEmpty(collection)) {
            return null;
        }
        Class<?> candidate = null;
        for (Object val : collection) {
            if (val != null) {
                if (candidate == null) {
                    candidate = val.getClass();
                } else if (candidate != val.getClass()) {
                    return null;
                }
            }
        }
        return candidate;
    }

    /**
     * Marshal the elements from the given enumeration into an array of the given type. Enumeration
     * elements must be assignable to the type of the given array. The array returned will be a
     * different instance than the array given.
     */
    public static <A, E extends A> A[] toArray(Enumeration<E> enumeration, A[] array) {
        ArrayList<A> elements = new ArrayList<A>();
        while (enumeration.hasMoreElements()) {
            elements.add(enumeration.nextElement());
        }
        return elements.toArray(array);
    }

    /**
     * Adapt an enumeration to an iterator.
     * 
     * @param enumeration
     *            the enumeration
     * @return the iterator
     */
    public static <E> Iterator<E> toIterator(Enumeration<E> enumeration) {
        return new EnumerationIterator<E>(enumeration);
    }

    /**
     * Iterator wrapping an Enumeration.
     */
    private static class EnumerationIterator<E> implements Iterator<E> {

        private final Enumeration<E> enumeration;

        public EnumerationIterator(Enumeration<E> enumeration) {
            this.enumeration = enumeration;
        }

        @Override
        public boolean hasNext() {
            return this.enumeration.hasMoreElements();
        }

        @Override
        public E next() {
            return this.enumeration.nextElement();
        }

        @Override
        public void remove() throws UnsupportedOperationException {
            throw new UnsupportedOperationException("Not supported");
        }
    }

    public static Map<String, String> valueToStringExcludeNull(Map<String, Object> map) {
        if (isEmpty(map)) {
            return Collections.emptyMap();
        }
        Map<String, String> reMap = new HashMap<>();
        for (Map.Entry<String, Object> entry : map.entrySet()) {
            if (StringUtils.isBlank(entry.getKey()) || null == entry.getValue()
                    || StringUtils.isBlank(entry.getValue().toString())) {
                continue;
            }
            String value = entry.getValue().toString();
            if (StringUtils.isBlank(value)) {
                continue;
            }
            reMap.put(entry.getKey(), value);
        }
        return reMap;
    }

    public static <E> void visitIterator(Iterator<E> dataList, BeanVisitor<E> visitor) {
        if (null != dataList) {
            while (dataList.hasNext()) {
                E next = dataList.next();
                if (null != next) {
                    visitor.visit(next);
                }
            }
        }
    }

    public static <E> void visitIterator(Collection<E> dataList, BeanVisitor<E> visitor) {
        if (null != dataList) {
            visitIterator(dataList.iterator(), visitor);
        }
    }

    public static <E, F> List<F> convertIterator(Iterator<E> dataList, final BeanToOtherConvertor<E, F> convertor) {
        final List<F> results = new ArrayList<>();
        visitIterator(dataList, new BeanVisitor<E>() {
            @Override
            public void visit(E bean) {
                F f = convertor.convertBeanToOther(bean);
                if (null != f) {
                    results.add(f);
                }
            }
        });
        return results;
    }

    public static <E, F> List<F> convertListOtherBean(List<E> dataList, final BeanToOtherConvertor<E, F> convertor) {
        final List<F> results = new ArrayList<>();
        visitIterator(dataList, new BeanVisitor<E>() {
            @Override
            public void visit(E bean) {
                F f = convertor.convertBeanToOther(bean);
                if (null != f) {
                    results.add(f);
                }
            }
        });

        return results;
    }

    public static <E, F> F convertOtherBean(E e, BeanToOtherConvertor<E, F> convertor) {
        if (null != e && null != convertor) {
            F f = convertor.convertBeanToOther(e);
            if (null != f) {
                return f;
            }
        }
        return null;
    }

    public interface BeanVisitor<E> {
        void visit(E bean);
    }

    public interface BeanToOtherConvertor<E, F> {
        F convertBeanToOther(E bean);
    }

    /**
     * Adds all elements in the iteration to the given collection.
     *
     * @param collection
     *            the collection to add to, must not be null
     * @param iterator
     *            the iterator of elements to add, must not be null
     * @throws NullPointerException
     *             if the collection or iterator is null
     */
    public static void addAll(Collection collection, Iterator iterator) {
        while (iterator.hasNext()) {
            collection.add(iterator.next());
        }
    }

    /**
     * Adds all elements in the enumeration to the given collection.
     *
     * @param collection
     *            the collection to add to, must not be null
     * @param enumeration
     *            the enumeration of elements to add, must not be null
     * @throws NullPointerException
     *             if the collection or enumeration is null
     */
    public static void addAll(Collection collection, Enumeration enumeration) {
        while (enumeration.hasMoreElements()) {
            collection.add(enumeration.nextElement());
        }
    }

    /**
     * Adds all elements in the array to the given collection.
     *
     * @param collection
     *            the collection to add to, must not be null
     * @param elements
     *            the array of elements to add, must not be null
     * @throws NullPointerException
     *             if the collection or array is null
     */
    public static void addAll(Collection collection, Object[] elements) {
        for (int i = 0, size = elements.length; i < size; i++) {
            collection.add(elements[i]);
        }
    }

    /**
     * Reverses the order of the given array.
     *
     * @param array
     *            the array to reverse
     */
    public static void reverseArray(final Object[] array) {
        int i = 0;
        int j = array.length - 1;
        Object tmp;

        while (j > i) {
            tmp = array[j];
            array[j] = array[i];
            array[i] = tmp;
            j--;
            i++;
        }
    }

    /**
     * Reverses the order of the given array.
     *
     * @param array
     *            the array to reverse
     */
    public static void toArray(final Object[] array) {
        int i = 0;
        int j = array.length - 1;
        Object tmp;

        while (j > i) {
            tmp = array[j];
            array[j] = array[i];
            array[i] = tmp;
            j--;
            i++;
        }
    }

    /**
     * Gets the size of the collection/iterator specified.
     * <p>
     * This method can handles objects as follows
     * <ul>
     * <li>Collection - the collection size
     * <li>Map - the map size
     * <li>Array - the array size
     * <li>Iterator - the number of elements remaining in the iterator
     * <li>Enumeration - the number of elements remaining in the enumeration
     * </ul>
     *
     * @param object
     *            the object to get the size of
     * @return the size of the specified collection
     * @throws IllegalArgumentException
     *             thrown if object is not recognised or null
     * @since Commons Collections 3.1
     */
    public static int size(Object object) {
        int total = 0;
        if (object instanceof Map) {
            total = ((Map) object).size();
        } else if (object instanceof Collection) {
            total = ((Collection) object).size();
        } else if (object instanceof Object[]) {
            total = ((Object[]) object).length;
        } else if (object instanceof Iterator) {
            Iterator it = (Iterator) object;
            while (it.hasNext()) {
                total++;
                it.next();
            }
        } else if (object instanceof Enumeration) {
            Enumeration it = (Enumeration) object;
            while (it.hasMoreElements()) {
                total++;
                it.nextElement();
            }
        } else if (object == null) {
            throw new IllegalArgumentException("Unsupported object type: null");
        } else {
            try {
                total = Array.getLength(object);
            } catch (IllegalArgumentException ex) {
                throw new IllegalArgumentException("Unsupported object type: " + object.getClass().getName());
            }
        }
        return total;
    }

    public static <T> List<T> getPagedList(List<T> data, int currentPage, int pageSize) {
        if (null == data) {
            return null;
        }
        if (data.isEmpty()) {
            return Collections.emptyList();
        }
        int fromIndex = (currentPage - 1) * pageSize;
        if (fromIndex < 0) {
            fromIndex = 0;
        }
        if (fromIndex >= data.size()) {
            return Collections.emptyList();
        }
        int toIndex = currentPage * pageSize;
        if (toIndex >= data.size()) {
            toIndex = data.size();
        }
        return data.subList(fromIndex, toIndex);
    }

}
